[PATCH] v9fs: fix races in fid allocation
[linux-2.6.git] / fs / 9p / vfs_file.c
index 1f8ae7d..a4799e9 100644 (file)
 int v9fs_file_open(struct inode *inode, struct file *file)
 {
        struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
-       struct v9fs_fid *v9fid = v9fs_fid_lookup(file->f_dentry, FID_WALK);
-       struct v9fs_fid *v9newfid = NULL;
+       struct v9fs_fid *v9fid, *fid;
        struct v9fs_fcall *fcall = NULL;
        int open_mode = 0;
        unsigned int iounit = 0;
        int newfid = -1;
        long result = -1;
 
-       dprintk(DEBUG_VFS, "inode: %p file: %p v9fid= %p\n", inode, file,
-               v9fid);
+       dprintk(DEBUG_VFS, "inode: %p file: %p \n", inode, file);
+
+       v9fid = v9fs_fid_get_created(file->f_dentry);
+       if (!v9fid)
+               v9fid = v9fs_fid_lookup(file->f_dentry);
 
        if (!v9fid) {
-               struct dentry *dentry = file->f_dentry;
                dprintk(DEBUG_ERROR, "Couldn't resolve fid from dentry\n");
+               return -EBADF;
+       }
 
-               /* XXX - some duplication from lookup, generalize later */
-               /* basically vfs_lookup is too heavy weight */
-               v9fid = v9fs_fid_lookup(file->f_dentry, FID_OP);
-               if (!v9fid)
-                       return -EBADF;
+       if (!v9fid->fidcreate) {
+               fid = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
+               if (fid == NULL) {
+                       dprintk(DEBUG_ERROR, "Out of Memory\n");
+                       return -ENOMEM;
+               }
 
-               v9fid = v9fs_fid_lookup(dentry->d_parent, FID_WALK);
-               if (!v9fid)
-                       return -EBADF;
+               fid->fidopen = 0;
+               fid->fidcreate = 0;
+               fid->fidclunked = 0;
+               fid->iounit = 0;
+               fid->v9ses = v9ses;
 
                newfid = v9fs_get_idpool(&v9ses->fidpool);
                if (newfid < 0) {
@@ -85,58 +91,16 @@ int v9fs_file_open(struct inode *inode, struct file *file)
                }
 
                result =
-                   v9fs_t_walk(v9ses, v9fid->fid, newfid,
-                               (char *)file->f_dentry->d_name.name, NULL);
+                   v9fs_t_walk(v9ses, v9fid->fid, newfid, NULL, NULL);
+
                if (result < 0) {
                        v9fs_put_idpool(newfid, &v9ses->fidpool);
                        dprintk(DEBUG_ERROR, "rewalk didn't work\n");
                        return -EBADF;
                }
 
-               v9fid = v9fs_fid_create(dentry);
-               if (v9fid == NULL) {
-                       dprintk(DEBUG_ERROR, "couldn't insert\n");
-                       return -ENOMEM;
-               }
-               v9fid->fid = newfid;
-       }
-
-       if (v9fid->fidcreate) {
-               /* create case */
-               newfid = v9fid->fid;
-               iounit = v9fid->iounit;
-               v9fid->fidcreate = 0;
-       } else {
-               if (!S_ISDIR(inode->i_mode))
-                       newfid = v9fid->fid;
-               else {
-                       newfid = v9fs_get_idpool(&v9ses->fidpool);
-                       if (newfid < 0) {
-                               eprintk(KERN_WARNING, "allocation failed\n");
-                               return -ENOSPC;
-                       }
-                       /* This would be a somewhat critical clone */
-                       result =
-                           v9fs_t_walk(v9ses, v9fid->fid, newfid, NULL,
-                                       &fcall);
-                       if (result < 0) {
-                               dprintk(DEBUG_ERROR, "clone error: %s\n",
-                                       FCALL_ERROR(fcall));
-                               kfree(fcall);
-                               return result;
-                       }
-
-                       v9newfid = v9fs_fid_create(file->f_dentry);
-                       v9newfid->fid = newfid;
-                       v9newfid->qid = v9fid->qid;
-                       v9newfid->iounit = v9fid->iounit;
-                       v9newfid->fidopen = 0;
-                       v9newfid->fidclunked = 0;
-                       v9newfid->v9ses = v9ses;
-                       v9fid = v9newfid;
-                       kfree(fcall);
-               }
-
+               fid->fid = newfid;
+               v9fid = fid;
                /* TODO: do special things for O_EXCL, O_NOFOLLOW, O_SYNC */
                /* translate open mode appropriately */
                open_mode = file->f_flags & 0x3;
@@ -163,9 +127,13 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
                iounit = fcall->params.ropen.iounit;
                kfree(fcall);
+       } else {
+               /* create case */
+               newfid = v9fid->fid;
+               iounit = v9fid->iounit;
+               v9fid->fidcreate = 0;
        }
 
-
        file->private_data = v9fid;
 
        v9fid->rdir_pos = 0;